Process for making a low sensitivity premium gasoline



PROCESS FOR MAKING A LOW SENSITIVITY PREMIUM GASOLIEE Filed July 6, 1959Patented Jan. l, 1963 3,071,535 .PROCESS FR MAKNG A LW SENSTFVETYPREMlUM GASOLINE .lohn A. Condrasky, Penn Hills, Pa., and Edwin M.Glazier, Fox Chapel Borough, Pa., assiguors to Gulf Research frDevelopment Company, Pittsburgh, Pa., a corporation of Delaware Fiied.iuly 6, i959, Ser. No. 825,@75 l Claim. (Cl. 208-55) This inventionrelates to a process for producing a premium gasoline of low sensitivityand more particularly to such a process employing a combination ofcatalytic cracking and alkylation.

Our process combines the use of catalytic cracking and alkylation withother rening procedures to produce a premium gasoline of lowsensitivity. By sensitivity is meant the difference between the researchmethod and motor method octane numbers of the gasoline. We use theshorter terms research method and motor method to refer to the 'standardASTM knock test methods, namely, the Test for Knock Characteristics ofMotor Fuels by the Motor Method (ASTM D357) and the Test for KnockCharacteristics of Motor Fueis by the Research Method (ASTM D908). Highresearch octane number is desirable for city driving at low enginespeeds and with frequent acceleration and high motor octane number isdesirable vfor highway driving at high engine speeds. Premium gasolinesnow being marketed frequently have high research octane number butunsatisfactorily low motor octane number. The octane rating sensitivity,or in other words, the diiference between motor and research octanenumber is too high. Typical premium gasolines now in use have asensitivity of or higher. The process of the present invention makespossible the production of premium gasolines, ie., gasolines having aresearch octane number (-}-,3 cc. TEL) of 97 or higher, that have asensitivity of 7.5 or less. This means that for a given research octanenumber the gasoline has a high motor octane rating. The process of theinvention produces high octane gasoline of low sensitivity by a novelcornbination of procedures for rening various refinery fractions andaccomplishes this result at a cost competitive with conventional reningprocedures that are unable to produce premium gasoline of lowsensitivity.

In processing crude oil for the production of premium gasoline it isknown to employ in combination duid catalytic cracking and alkylation.The catalytic cracking charge normally comprises a straight run gas oilfraction of the crude oil. Conventionally, the aim of the catalyticcracking operation is to produce from the straight run middle distillateor gas oil a maximum yield of gasoline range hydrocarbons. The catalyticcracker is run at a space velocity and temperature providing a crackingseverity such that the amount of butenes produced do not exceed theamount that can be alkylated with isobutane recoverable from the crudeoil and available for alkylation, a portion of the n-butane recoverablefrom the crude being required for blending with the final gasolineproduct to raise its vapor pressure to the required level. In otherWords, in conventional practice, the severity of the catalytic crackingoperation and the consequent yield of light olens is limited by theyield of butanes from the particular crude oil being processed.

We have now discovered that premium gasoline of unusually lowsensitivity can be produced economically by maximizing the alkylationphase of crude oil processing. We can accomplish this result byemploying, in combination, high severity fluid catalytic cracking,alkylation, coking of reduced crude and by employing in the alkylationstage butanes obtained from an outside source.

In accordance with our procedure, after fractionating the crude oil toobtain straight run gas oil cracking charge and other straight runproducts, the crude oil residuum is subjected to coking to obtainadditional gas oil cracking charge. The catalytic cracking unit is thenoperated, not at conventional conditions for maximum production ofgasoline range hydrocarbons, but at severe conditions to obtain a highyield of C5 and lighter olens :as alkylation charge stock. In ourprocedure all of the butenes and at least a portion of the pentenesobtained by catalytic cracking are subjected to alkylation. We employcracking conditions of severity such that the yield of these olefinsexceeds the yield that can be alkylated with the isobutane availabledirectly or indirectly from the crude oil. Accordingly, we use isobutanederived from an outside source for alkylation and thus markedly increasethe production of alkylate. The alkylate being a mixture of branchedchain paraflins of high motor octane rating contributes greatly as ablending component to our ultimate production of premium gasoline of lowsensitivity.`

ln the preferred embodiment of our process we employ additionalprocesses that yield gasoline range hydrocarbons, some of which yieldproducts rich in branched chain paraftns and, therefore, contribute toproduction of a high octane premium gasoline of low sensitivity. Theseadditional processes include catalytic isomerization of C5 and C6parafns, catalytic reforming of straight run naphtha and catalyticpolymerization of propylene.

Our process in general comprises charging a total crude oil tofractional distillation to obtain straight run fractions including agaseous fraction, a C4 fraction, a gasoline fraction, a gas oil fractionand a residual fraction. The residual straight run fraction is subjectedto coking to recover coking products including a fuel gas, propylene,C4-C5 olens, a naphtha fraction, a gas oil fraction and coke. Thestraight run gas oil fraction and the coker gas oil fraction are subjectto uid catalytic cracking at severe conditions including a temperatureof at least 975 F. to achieve conversion of at least 70 volume percentof the fresh cracking charge and thereby to produce C4 olefins in aImolar yield greater than the molar yield of butanes recovered from thestraight run distillation of the crude oil and from conversion productsof the straight run fractions of the crude oil less the amount ofn-butane required for vapor pressure adjustment of the final gasolineproducts. All of the C4 olens and at least a portion of the C5 olefinsproduced by fluid catalytic cracking and coking are subjected toalkylation with all of the butanes obtained directly and indirectly fromthe crude oil and with butanes obtained from another source. Inpreferred embodiments of the process, straight run gasoline is subjectedto catalytic reforming, propylene fractions from catalytic cracking andcoking are coking are subjected to catalytic polymerization and astraight run paratlin fraction of the C5-C6 range is subjected tocatalytic isomerization. A high octane premium gasoline of lowsensitivity is produced by blending at least portions of the alkylate,the reforming product and the catalytic isomerization product.

We will describe our process in more detail by reference to the drawingwhich is a schematic flow diagram of an embodiment of our process.

Total crude oil is fractionated in a conventional atmospheric-vacuumcrude distillation unit tu. This equipment comprises an atmosphericfractionating column for topping the crude oil and a vacuum tower forfractionating the topped crude oil to obtain gas oil for catalyticcracking charge stock and vacuum reduced crude for coking charge stock.The products of the atornsphericvacuum distillation include fuel gas; aC., stream of n-butane and isobutane; a C5 to 190 F. fraction containingn-pentane, sopentane, n-hexane and the branched chain hexanes; a

amnesia 3 190 to 375 F. straight run gasoline fraction; a 370 to 620 F.straight run furnace oil fraction; a 620 to 1050 F. heavy gas oilfraction and vacuum reduced crude.

The straight run C4 fraction is charged by line li to the alkylationunit 12. The C5 to 190 F. fraction is charged by line 14 to thehydroisornerization unit The 190 to 375 F. straight run gasolinefraction is charged by line i6 to the catalytic reforming unit i3. The375 to 620 F. fraction is charged by line 19 to hydrogen treating unit20 where it is upgraded for light fuel oil blending. The heavy gas oilfraction is charged by line 2l to the fluid catalytic cracking unit 22.Vacuum reduced crude is charged by line 2.3 to the delayed coking unit24.

The coker Z4- is operated according to the technique of delayed cokingprincipally to produce gas oil cracking charge from the vacuum reducedcrude. in this type of process the reduced crude is heated to a hightemperature, e.g., 920 F., and is passed into a coking drum Where it is`maintained at high temperature for a sufficient length of time tothermally crack or decompose the reduced crude and produce lighterhydrocarbons and coke. Coke forms on the Walls of the drum. After onedrum is lled with coke the operation is switched to another drum and thecoke is removed mechanically or hydraulically from the rst drum.

The hydrocarbon stream from lthe coking drum is fractionated and, asshown in the drawing, several fractions are recovered. A light gasfraction is withdrawn by line 25 as fuel gas. A C3 fraction rich inpropylene is charged by line 25 to the catalytic polymerization unit 28.A C4 fraction containing n-butane, isobutane, n-butene and isobutyleneis charged by line 29 to the alkylation unit 12. A coker C5 fractionconsisting mainly of pentanes and pentenes is charged to gasolineblending by line 30. Preferably, the coker C5 fraction and a Cfr-400 F.gasoline fraction from catalytic cracker 22 are sweetened beforegasoline blending is a conventional gasoline sweetening unit 45 whereinobjectionable forms of sulfur, eg., mercaptans, are converted to lessobjectionable form. A coker naphtha fraction of C5 to about 400 F. rangeis charged by line 31 to the hydrogen treating unit 20. The heaviestliquid product of the coking reaction, the coker gas oil which consistsof all of the liquid product higher boiling than about 400 F., ischarged by line 32 to the fluid catalytic cracking unit 22.

The fresh charge to the fluid catalytic cracking unit 22 thus consistsof heavy straight run gas oil charged by line 21 and the coker gas oil,400 F. pius, charged by line 32, The catalytic cracking unit is aconventional fluid catalytic cracker wherein a suspended bed of powderedsilica-alumina catalyst 'is contacted at high temperature with anupflowing stream of vaporized hydrocarbon charge stock. An essentialfeature of our process is that the catalytic cracking is carried out ata higher than conventional temperature of at least 975 F. and preferablyin the range 975 to 1050 F. The space velocity of the total hydrocarboncharge stock is selected in accordance with the cracking temperature toprovide cracking conditions of suiiicient severity to achieve conversionof at least 70 volume percent of the fresh cracking charge and therebyto make a high yield of C5 and lighter olefns.

More specifically, the cracking conditions are of such severity that fora given amount of crude oil charged to the primary distillation unit,the number of mols of butenes produced by catalytic cracking is greaterthan the number of mols of available butanes obtained from the sameamount of crude oil either directly in the straight run C4 fraction ofthe crude oil or indirectly by recovery from conversion products offractions of the crude oil such as the C4 fraction of the cokingproducts and the C4 fraction of the reformate. By available butanes Wemean the aomunt of isobutane, or of n-butane which can be isomerized toisobutane as needed for alkylation, in excess of the amount required inthe form of n-butane for blending with final gasoline products to obtainthe required vapor pressure. Consequently, in accordance with ourprocess, to supply the total amount of isobutane required for alkylatingall of the C4 oleiins produced by catalytic cracking of gas oilfractions derived from the crude oil, butane from another source issupplied to the alkylation unit. Such butane is referred to herein asoutside butane and can be supplied either as isobutane or as n-butanewhich is isomerized to isobutane as needed.

The butenes produced by catalytic cracking exceed the amount that can bealkylated by the available butanes. Eutenes for alkylation are alsoproduced to some extent in the coking unit. Furthermore, at least aportion of theV pentenes produced by catalytic cracking are aikyated,Accordingly, a considerable amount of outside butane is required tosupplement the available butane for alkylating both sources of butenesand at least a portion of the pentenes from the catalytic cracker. Theproduction of pentenes as alkylation charge is not a deliberate obiectof our process. However, by operating the catalytic cracking unit athigh severity to obtain a high yield of butenes as alkylation charge wealso make more pentenes than can be accommodated as blending componentsof the nal gasoline. Accordingly, in our process we subject toalkylation at least a portion of the pentenes produced in catalyticcracking so that the remainder of the C5 olens can be accommodated inthe gasoline products without exceeding the amounts permitted within theVolatility specifications of the gasoline.

As shown in the drawing, the charge to the alkylation unit l2 consistsof the straight run C4 fraction charged by line li, the C4 fraction ofthe catalytic reforming product charged by line 34, the C4 fraction fromthe delayed coking unit charged by line 29, the product of isomerizationof outside n-butane introduced by line 36 and the C4-C5 fraction of thefluid catalytic cracking product introduced by line 37.

The alkylation unit 12 can operate according to any of the knownalkylation procedures in which isobutane reacts in equi-molecularproportions with C4 olens, and in our process with C5 olens, to producebranched chain paraiiins having 8 or 9 carbon atoms in the molecule. Theschematic drawing omits details of the alkylation process but theseare'well-known and any of the known procedures and equipment can beused. The feed containing olens and isobutane, as Well as n-butane whichis mixed with the isobutane and which passes through the alkylationreactor without being converted, is contacted in the liquid phase withan alkylation catalyst such as a concentrated sulfuric acid catalyst ata temperature of 35 to 45 F. or with a hydrofluoric acid catalyst at atemperature of 45 to 100 F. In order to prevent polymerization andcontrol the alkylation reaction the feed will contain a high ratio ofisobutane to olelins, for example, a mol ratio in the range of 3:1 to6:1. The alkylate stream is deisobutanized and debutanized. Theisobutane or a portion thereof can be recycled to the aikylation unitand the n-butane or a portion thereof can be passed by line 33 to thebutane isomerization unit 39 to produce isobutane for the alkylationreaction. Alternatively, the n-butane or a portion thereof can beblended with the iinal gasoline product to control its vapor pressure.

The butane isomerization unit 39 can operate according to any of theknown catalytic isomer-ization procedures. rthe process can be a lowtemperature (e.g., to 500 F.) liquid phase isomerization processemploying a Freidel-Crafts type of catalyst such as aluminum chloride orit can be one of the more recently developed procedures which empolys asolid reformingtype catalyst such as halogen-promotedplatinum-onalumina. in this type of process the butane charge stock iscontacted with the catalyst in the vapor phase at high or moderatetemperature, e.g., 7002900" in the pres;-

ence of hydrogen. The charge stock for the butane isomerization unitwill include outside n-butane, that is to say, butane obtained from asource other than the crude oil charged to the atmospheric-vacuum crudedistillation unit 10. The outside butane, which is introduced to theisomerization unit by line 52, can be obtained directly or indirectlyfrom other crude oil sources or from natural gas or natural gasoline.The charge to the unit can also comprise recycled n-butane from thealkylation unit and n-butane from various product streams of theprocess, as shown in the drawing.

In addition to the principal units which have been discussed, eg., theatmospheric-vacuum distillation unit, the alkylation unit, the fluidcatalytic cracking unit and the coking unit, certain other upgradingprocedures are employed in the preferred form of our process and thesecontribute to the production of a high octane, low sensitivity premiumgasoline. Thus, the process can employ a catalytic isomerization unit towhich is charged, erg., a straight run C5-l90 F. fraction withdrawn fromthe distillation unit by line 14. The isomerization unit 15 preferablyincludes a prefractionator, not shown in the drawing, for separatingisoheptanes and heavier from C5-C5 parafns of the C5-l90 F. fraction,the isoheptane and heavier being passed, if desired, to hydrogentreating unit 50 for desulfurization and the C5-C6 fraction beingcharged to the isomerizaton reactor or reactors of unit 15. Preferably,the C5-C5 fraction is fractionally distilled to obtain a highlyconcentrated n-pentane fraction and a fraction highly concentrated inn-hexane and methylpentanes. Then these fractions are separatelyisomerized, preferably over a halogen-promoted, platinum-aluminacatalyst in the presence of hydrogen.

The efuent from the isomerization reactors can be fractionated torecover unconverted n-pentane, n-hexanes and methylpentanes which arerecycled to the isomerization reactors. The branched chain parainproducts are blended with the final gasoline product and, being branchedchain paraflins of high research and motor octane ratings, theycontribute to the low sensitivity of the high octane premium gasolineproduct of our process.

As We have indicated, the charge to the catalytic reforming unit 13comprises the straight run 190 to 375 naphtha fraction withdrawn fromthe atm0spheric-vacnum distillation unit by line 16. Another suitablereforming charge stock is the fraction of similar boiling range obtainedby hydrogen treating a C6 to 400 F. fraction of 4the coking product.This fraction is subjected to mild hydrogen treatment in the hydrogentreating unit by contact with a hydrogenation catalyst such as cobaltmolybdate on alumina in the presence of hydrogen at a temperature of 600to 800 F. Specific conditions suitable for this hydrogen treatmentinclude `a temperature of 675 F., a pressure of 600 pounds per squareinch gauge, a liquid hourly space velocity of 8 volumes per volume perhour and a hydrogen circulation rate of 4,000 standard cubic feet perbarrel with a hydrogen consumption of 200 standard cubic feet perbarrel. The hydrogen treatment saturates `and desulfurizes the cokernaphtha but reduces its octaine rating. The hydrogenated coker naphtharequires octane improvement before it can be lsatisfactorily employed asa premium gasoline component. Accordingly, the hydrogen treated fractionis charged by line 40 to the catalytic reformer 18.

The `catalytic reformer can be any of the conventional units employedfor upgrading naphtha fractions wherein such reactions as aromatization,dehydrogenation, isomerization and hydrccracking occur. The naphthacharge stock is contacted with -a reforming catalyst such asplatinum-alumina or molybdena-alumina in the presence of hydrogen latelevated pressure and temperature, e.g., 400 to 600 pounds per squareinch gauge and 850 to 950 F. The reformate is fractionated to separate ahydrogen-rich gas which is recycled to the reforming unit and a C4fraction which can be passed by line 34 to the' alkylation unit 12. Thereformate withdrawn by line 41 is of high octane rating and is charged.to the inal gasoline product blending unit.

Another unit employed in the preferred form of our process is thecatalytic polymerization unit 28. In this unit the various olefinic C3streams produced in the process are contacted with a polymerizationcatalyst such as phosphoric acid to polymerize the propylene and producean olenic polymer gasoline which, because of its rather high octanesensitivity, is used as a blending component for the regular gradegasoline rather than for the premium grade gasoline.

An important stage of our process is the blending of the gasolinecomponents. Products available for gasoline blending include `alkylatefrom alkylation unit 12; reformate from reforming unit 18; sweetenedgasoline, including the sweetened coker C5 fraction and the sweetenedFCC C5-400" F. fraction from sweetening unit 45; isopentane and branchedchain hexanes from C5C6 isomerization unit 15; and polymer vgasolinefrom catalytic polymerization unit 28. To adjust vapor pressure to therequired level, eg., to Ia Reid vapor pressure of 10 pounds per squareinch, n-butane is added to the gasoline blend. This can be n-butanerecovered from the Ialkylation unit 12 and/ or outside n-butane.

Besides the above main gasoline components other products for gasolineblending include a small amount of pentanes recovered from the butaneisomerization product of unit 39 and the hydrogen-treated gasolinefraction from hydrogen treating unit 50. In the latter unit a light gasoil from catalytic cracking and a Cq-I- fraction from the isomerizationunit 15 prefractionator `are desulfurized by contact with hydrogen and ahydrogenaton catalyst, eg., `cobalt molybdate on alumina, at, forexample, 700 F., 600 p.s.i.g., space velocity of 4 vol./ VOL/hr. andhydrogen rate of 4,000 sci/bbl.

The other principal liquid product of our process is No. 2 fuel oil.This product is formed by blending the hydrogen-treated light FCC gasoil from hydrogen treating unit 50; the hydrogentreated coker naphtha,370 to 400 F. and straight run furnace oil from hydrogen treating unit20. Other products of our process include fuel gas which is recoveredfrom the diferent units as indicated and petroleum coke obtained fromdelayed coking unit 24. Another product is heavy gas oil recovered fromcatalytic cracking unit 22. If desired, this product can be fractionatedto obtain a light fraction suitable as No. 5 fuel oil and a heavyfraction which is employed as refinery liquid fuel. p

From the above description it can be seen that butanes are employed fortwo ultimate purposes in our process. They are used to provide isobutanefor alkylation with the C4 and C5 olens in the alkylation unit 12 and toprovide n-butane for blending with the iinal gasoline product to raisethe vapor pressure thereof to the required level. We have shown that thesources of the butanes include a straight run C4 fraction obtaineddirectly from the crude oil and other streams obtained indirectly fromthe crude oil such as a C4 stream from the delayed coking unit 24, a C4stream from the fluid cracking unit 22, an isobutane stream from thebutane isomerization unit 39 and a C4 stream from the reforming unit 18.

The other source of butane is the outside butane stream 52 which can beobtained, for example, from another crude oil or from natural gas ornatural gasoline. We refer throughoutl this specication to the fact thatthe catalytic cracking unit is operated under conditions of suchseverity as to yield a greater amount of C4 oleiins than can bealkylated with the available isobutane obtained directly and indirectlyfrom the crude oil. By this we mean that the amount of butanes obtainedfrom the particular crude oil is insuiiicient to supply :isobutane foralkylating all of the C4 olefins produced in the catalytic crackingstage and to provide butanes as required for blending With the nalgasoline products. Consequently, an outside butane stream is introducedinto the process. It should be understood that the outside butane can beused either for gasoline blending or can be isomerized and used foralkylation. If the outside butane stream is employed for gasolineblending, it may very Well be that the butanes obtained directly andindirectly from the crude oil will be suicient for alkylation but, theamount will be inadequate to supply the over-all requirement. Therefore,it should be understood that when we refer to the 10 fact that the fluidcatalytic cracking stage is carried out at such severity as to yield agreater amount of C4 oleus than can be alkylated with the isobutaneobtained from vthe crude oil, we are defining the relative yields ofbutanes and of C4 oletins, Whether the butanes obtained from 15 thecrude oil are employed for alkylation or for ual product blending isimmaterial. The important fact is that outside butanes must be added tothe butanes obtained from the crude oii to meet the over-all requirementfor alkylation and gasoline blendin. 20

The following example illustrates results obtainable with our process.

3 EXAMPLE In this example, 100,000 barrels per calendar day (hereinafterabbreviated as b./c.d.) of Kuwait crude oil of 31.5 API gravity isprocessed by our new procedure to produce regular and premium lgradegasolines in a volume ratio of 40 to 60. In this operation the fluidcatalytic cracking unit operates at a temperature of 975 F. and achieves71.5 percent conversion of the fresh cracking charge which consists ofstraight run and coker gas oil fractions. An outside butane stream isintroduced into the system at a rate of 3,406 b./c.d. The yield ofpremium gasoline having a research octane rating (TEL content: 2.7 cc./gal.) of 102.7 and a sensitivity of 7.5 is 22,892 b./c.d. The yield ofregular gasoline having a research octane rating (TEL content: 2.7cc./ga1.) of 95.7 and a sensitivity of 11.2 is 34,337 b./c.d. Details asto the charge and product streams for each of the process units aregiven in Tables I through IV below. In the tables the yields of gaseousVproducts such as fuel gas are reported as barrels per day of fuel oilequivalent, the latter being abbreviated in the tables as FOB Table IFinal products Atmosphericwacuum distillation:

barge: Kuwait: crude Products:

Fuel gas, FOE SR C4 fraction SR gaso., C5490" F SR naphtha, 190-375 F-SR furnace oil, 375-620 F SR hvy. gas oil, 620-1,050 F. Vacuum bottoms,1,050o F.-l- Delayed coking:

Charge: Vacuum bottoms Products:

Fuel gas, FOE Coker C3 fra Miou B,/c.d. 100, 000

115 Fuel gas, 115 b./c.d.

884 Fuel gas, 884 b./c.d.

FCC hvy. gas oil.

233 No. 5 fuel oil, 233 b./c.d.

Hvy. gas oiH-decan ed 01., 2, 154 Rcfin. fuel, 2,154 b./c.d. Catalyticpolymerization:

Charge:

Coker C3 fraction 621 FCC C3 fraction 4,230

Products:

C3 fuel gas, FOE Polymer gasoline 1, 552 Fuel gas, 1,552 b./c.d.

Alkylation:

Charge: B./c.d. B./c.d. SR C4 frac 2, 241 i-Butane 5, 811 Coker C4 frac.488 n-Butane 4, 050 FCC C4-C5fra 7, 547 Butenes" 4, 556 Isom. unit i- 4.3, 248 Pentanes.. 387 Platformer Cis 2, O07 Pentenes 727 Total 15, 531Total 15,531 B./c.d. Products:

n-But'me 4, 050 Alkylate 9, 368 Fontane-hexane hydroisomerization:

Charge:

SR gaso., (E5-190 F 7, 549 Platormer oft-gas (360,000 s.c.f./c.d.).Products:

Fuel gas, FOE 156 Fuel Gas, 15G b./c.d. i-Pentane 2, 873 i-Tll'e 'aries2, 792 i-Heptaues. 1, 796 Butaue isomerization (l ase, A1013 c Charge:u-Butane (from etal of 3,400 b./C.d. outside 3, 352

butane and 4,050 b./C.d. n-butane from alkylation unit).

Table I-Continued Final products Hydrogen treating (A):

Charge: B./c.d.

FCC lt. gas oil 10,555 i-Heptanes l, 796 Platormer oigas (4,230,000s.c,f./c.d.). Products:

Fuel gas, FOE 334 Fuel gas, 334 b./c.d. Hydro-treated gasoline 1, 825Hydrotroated FOC light gas oil 550 Hydrogen treating (B):

Charge:

SR furnace oil, 375-620 F 20, 900 Coker naptlia, C-400 F Platforrnorott-gas (5,200,000 s.c.f./c.d.). Products:

Fuel gas, FOE 529 Fuel gas, 529 b./c,d. Hydro-treated eoker naphthaCri-370 F 3, 747 370-400 F 72s Hydro-treated SR furnace oil 20, 750Platforming:

Charge:

SR naphtha, 190-375 F 15,700 Hydro-treated coker naphtlia, Ca370 F 3,747 Products:

Fuel gas, FOE 1, 598 Fuel gas, 1,598 b./c.d. H2 separator gas (9,700,000s.c.i./c.d.). C4 fraction 2, 007 Reformate 14, 916 Gasoline sweetenng:

Charge:

Coker C, fr'ir-iinn 177 FCC C5 fraction 4,393 FCC gaso., Cri-400 F.-15,052 Products: sweetened gasoline 19, 622 Gasoline blending:

Charge:

Pentane from butancisoinerization 84 sweetened gasoline (coller C5, FCOC5-400 F.) 19,622 Polymer gasoline 1, 645 Alk ate.. 9,368 i-Pcntane fromC5-Ce isomerization. 2, 873 i-Hexanes from (l5-C5 isonierization 2, 792Hydro-treated gasoline 1, 825 Refornmte 14, 916 Butaries (from total of3,400 b./o.d. outside lontane 4,104

and 4,050 b./c.d. n-butane from alkylation unit). Products:

Premium gasoline 22, 892 Premium gasoline, 22,892 b./c.d. Regulargasoline, 34. 337 Regular gasoline, 34,3 7 b./c,d. No. 2 fuel oilblending;

Charge:

Hydro-treated light gas oil 10, 20, 750 Products: N o. 2 fuel oil 32,037 No. 2 fuel oil, 32,037 b./o.d.

the component to 10 pounds per square inch absolute. Table Il Sincebutanes are included with various gasoline compo- SUMMARY 0F CHARGE ANDPRODUCTS nents the butanes are not listed as a separate component as inthe blending stage of Table I. Vol. B./c.d. T./c.d. percent Table IIIPREMIUM GASOLINE Cha-e: t d O0 o 0 Components: B./c.d.

uwai cru e 1 0 10 ,000 Banane 3.4i ,406 Aikyla o 10302 Proiaucts: 1 2289 9 2 Light reformate (I.B.P.-269 F.) 544 remiuin gaso ine Q 89 o Hema,gasoline 34. 34 34, 337 Heavy reformat@ (269 EP) 6,150 02?? 3g. 32,Light FCCl (LBR-200 F.) 3,600 0.5 ue o yemleum 1 p Isopentane 2,296Refinery fuel (liquid) FOE 2.15 2, 154 Reneryfuei (gas) Fon 0.30 9,301Total l Total 100.95 100, 054 Octane rating:

Research, +2.7 cc. TEL/gal 102.7 In Table I We have shown all of thegasoline compo- .MOOY +27 CC- TEL/gal 952 nents as being charged to ,thegasoline blending stage for Sensltlvlty 7-5 premium and regular gasolineproducts. In actual prac- REGULAR GASOLINE tice the components or theirproportions will be diiferent Components: B./c.d.

l 0 for the premium and regular grade products. Table III Llght FCC(LBR-200 F) 5,030

v l n C below illustrates amounts of the various gasoline compo- HeavyFCC (200 FEP) 12,693 nents of Table I that can be employed in formingpremium PG13/mel' 1,870

n l 0 gasoline and regular gasoline in our process when proc- Llghtreformat@ (LBR-269 FJ 7,722 essing 100,000 b./c.d. of Kuwait crude.Table III also Heavy reformate (269 F.-EP) 2,227 lists the octanenumbers of these products. All data in Hydro-treated gasoline 1,991 thistable are reported on the basis of 10 pounds Reid Isghexanes 2,804 vaporpressure. In other Words, the amount of each gaso- Total w34 337 linecomponent reported in Table III includes butanes in 1 I 1 d l C y y anamount suicient to raise the Reid vapor pressure of less cfshtlms 'andC5 s from humm somematon i 1 Table ILL-Continued REGULARGAsoLrNn-oontinued Octane rating: B./c.d. Research, +2.7 cc. TEL/gal95.7 Motor, +2.7 cc. TEL/gal 84.5

Sensitivity 11.2

Table III illustrates one suitable blending combination for thedifferent gasoline components produced in our process. In thisparticular blending scheme all of the high yield of 10,302 b./c.d. ofalkylate is used in the premium gasoline product. Since our processproduces other fractions rich in branched chain parains, e.g., branchedchain C and C5 parain fractions and light reformate, and since thebranched chain paraffins have good research and motor octane ratings, itis possible to vary the combination considerably and still produce ahigh yield of premium gasoline of very high research octane rating andlow sensitivity.

We have indicated that our process produces high octane gasoline of lowsensitivity at a cost competitive with conventional rening proceduresthat are unable to produce premium gasoline of low sensitivity.Furthermore, our process achieves this result at lower cost per gallonthan other procedures aimed at producing high octane gasoline of lowsensitivity. This can be demonstrated by comparison of the embodiment ofour process as described in the foregoing example and in Tables I, IIand III, with the results of other procedures which are intended forproducing high octane premium gasoline and which employ certain processelements in common with our process. One such process, which we willrefer to as process A, employs atmospheric-vacuum distillation, delayedcoking of vacuum bottoms, uid catalytic cracking of straight run andcoker gas oils, catalytic polymerization of propylene, alkylation ofbutylenes with isobutane, catalytic reforming of straight run naphthaand hydro-treated coker naphtha, as well as such additional elements ashydro-treating and gasoline sweetening of fractions similar to thosethat are subjected to such treatments in our process. An essentialdifference between process A and our process in the embodiment describedin the example and tables is that in process A the liuid catalyticcracking unit is operated under conventional conditions to achieve 65percent conversion whereas in our process the liuid catalytic crackingis carried out at 975 F. to achieve 71.5 percent conversion. As aresult, in process A outside butanes are not required for alkylating theC4 and C5 oleins produced by fluid catalytic cracking. The butanesobtained from the crude oil are adquate for the alkylation stageand forvapor pressure adjustment of the gasoline products. Other differencesare that the preferred form of our process employs hydroisomerizationfor upgrading low octane rating C5 and C5 parains and employs butaneisomerization for isomerizing either outside n-butane or n-butaneobtained from the crude oil whereas process A does not.

In still another comparable operation which we designate as process Bmost of the procedures employed in our process are employed but, insteadof linid catalytic cracking, process B employs thermal cracking ofstraight run and coker gas oils. In process B all of the butanesemployed for alkylation and gasoline blending are obtained directly orindirectly from the crude oil.

A comparison of the results obtainable in our process and in processes Aand B is given in Table IV below. The table lists yields of variousproducts in processing of 100,000 b./c.d. of Kuwait crude for productionof premium and regular gasolines in a 60:40 ratio and shows thecomparative costs per gallon of the gasolines produced.

l2 Table 1V Iuven- A B tion Premium gasoline (l0 RVF):

Yield, bb1./100,000 bbl. crude Octane ratings:

Table IV shows that process A makes a premium gasoline at slightly lesscost than our process but the sensitivity is 13.0 as compared with 7.5for our process and the research octane number is only 101.0 as comparedwith 102.7 for our process. In process B the sensitivity of the gasolineis low but the research octane rating is lower than in our process andthe cost is substantially higher. With respect to the regular gradegasoline products, the product of our process has a higher researchoctane rating than that of either process A or B and the cost per gallonfor our product is almost as low as that of process A and issubstantially lower than that of process B. From these results it can beseen that our process is markedly superior economically to other methodsof making high octane premium gasoline of low sensitivity. A majordifference between our process and the other two processes is seen inthe alkylate yield as reported in Table IV. For a crude charge of100,000 barrels the alkylate yield for our process is 10,302 barrels ascompared with only 4,766 barrels for process A and 4,195 barrels forprocess B.

The foregoing example and tables show that We have developed a valuablenew combination of refining procedures for producing a high yield ofhigh octane rating premium gasoline of low sensitivity. We accomplish anew result through a new combination of procedures which include Y(1)the use of high lluid catalytic cracking temperature to produce maximumbutenes for use as alkylation charge stock, the iluid catalytic crackingunit being operated at 975 F. or higher to achieve conversion of thecracking charge of at least 70 volume percent, (2) alkylating totalbutene production, plus a portion of the pentenes to the extent requiredby gasoline volatility restrictions, and (3) isomerizing outside butaneto provide adequate isobutane for alkylation.

Obviously many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and therefore only such limitations should be imposed asare indicated in the appended claim.

We claim:

-A process for making low sensitivity premium gasoline which comprises:

fractionally distilling a total crude oil to obtain a straight run C4fraction, a straight run C5 to 190 F. light gasoline fraction, astraight run gas oil having an initial boiling point of about 620 F. anda straight run residuum;

`coking said straight run residuum, and recovering converson productsincluding C4 olelins, n-butane, isohutane, a coker gasoline fraction andcoker gas oil; subjecting said straight run gas oil and said coker gasoil to iluid catalytic cracking and recovering conversion productsincluding C4 olens, n-butane, isohutane, C5 oletins and a crackedgasoline fraction; said fluid catalytic cracking occurring at severecondi tions, including a temperature of at least 975 F., suiicient toachieve conversion of at least 70 volume 13 iiipercent of said catalyticcracking charge to produce with isobutane from `another source andrecovering a molar yield of C4 olefns greater than the numan alkylatetherefrom; ber of mo'ls of n-butane and isobutane recovered by andblending said alkylate with said aforementioned straight runfractionation of said crude oil and by gasoline fractions to produce apremium gasoline fractionation of said conversion products minus the 5having an octane rating sensitivity no greater than mols of butanesrequired for vapor pressure ad- 7.5.

justment of the nal gasoline products;

subjecting all of said C4 oleins produced by said uid References Citedin the me of this Patent catalytic cracking and coking operations and atUNITED STATES PATENTS least a portion of the C5 olens produced by said10 2,360,622 Roetheu OGL 17, 1944 uid catalytic cracking to alkylationwith all of the 2,415,530 porter F511 11, 1947 isobutane obtaineddirectly and indirectly from frac- 2,644,785 Harding et a1 July 7, 1953tion of said crude and said conversion products and 2,905,619 SutherlandSept. 22, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OE CORRECTIONPatent No. 3,071,535 `Ianuary l, 1963 John A. Condrasky et al.

It s hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 2, line 54, strike out are cokng"; line :37, for

"subjegt" read subjected column 3, line 2, for "620" read 620 line 38,for "is" read in line 7l, for "products" read product same column 3,line 73, for "aomunt" read amount column 4, line l after "with" o insertthe column 5, line 44, for "375" read 375 F. Columns 9 and IO, TableI-Continued, first column, line 32 thereof, for "Coker C, fraction" readCoker C5 fraction Signed and sealed this 21st day of January 1964,

(SEAL) Attest:

ERNEST W SWIDER EDWIN L.; REYNOLDS AC i D Q' Commissioner of PatentsAttestng Officer

1. A PROCESS FOR MAKING LOW SENSITIVITY PREMIMUM GASOLINE WHICHCOMPRISES: FRACTIONALLY DISTILLING A TOTAL CRUDE OIL TO OBTAIN ASTRAIGHT RUN C4 FRACTION, A STRAIGHT RUN C5 TO 190* F. LIGHT GASOLINEFRACTION, A STRAIGHT RUN GAS OIL HAVING AN INITIAL BOILING POINT OFABOUT 620*F. AND A STRAIGHT RUN RESIDUUM; COKING SAID STRAIGHT RUNRESIDUUM, AND RECOVERING CONVERSON PRODUCTS INCLUDING C4 OLEFINS,N-BUTANE, ISOBUTANE, A COKER GASOLINE FRACTION AND COKER GAS OIL;SUBJECTING SAID STRAIGHT RUN GAS OIL AND SAID COKER GAS OIL TO FLUIDCATALYTIC CRACKING AND RECOVERING CONVERSION PRODUCTS INCLUDING C4OLEFINS, N-BUTANE, ISOBUTANE, C5 OLEFINS AND A CRACKED GASOLINEFRACTION; SAID FLUID CATALYTIC CRACKING OCCURRING AT SEVERE CONDITIONS,INCLUDING A TEMPERATURE OF AT LEAST 975*F., SUFFICIENT TO ACHIEVECONVERSION OF AT LEAST 70 VOLUME PERCENT OF SAID CATALYTIC CRACKINGCHARGE TO PRODUCE A MOLAR YIELD OF C4 OLEFINS GREATER THAN THE NUMBER OFMOLS OF N-BUTANE AND ISOBUTANE RECOVERED BY STRAIGHT RUN FRACTIONATIONOF SAID CRUDE OIL AND BY FRACTIONATION OF SAID CONVERSION PRODUCTS MINUSTHE MOLS OF BUTANES REQUIRED FOR VAPOR PRESSURE ADJUSTMENT OF THE FINALGASOLINE PRODUCTS; SUBJECTING ALL OF SAID C4 OLEFINS PRODUCED BY SAIDFLUID CATALYTIC CRACKING AND COKING OPERATIONS AND AT LEAST A PORTION OFTHE C5 OLEFINS PRODUCED BY SAID FLUID CATALYTIC CRACKING TO ALKYLATIONWITH ALL OF THE ISOBUTANE OBTAINED DIRECTLY AND INDIRECTLY FROM FRACTIONOF SAID CRUDE AND SAID CONVERSION PRODUCTS AND WITH ISOBUTANE FROMANOTHER SOURCE AND RECOVERING AN ALKYLATE THEREFROM; AND BLENDING SAIDALKYLATE WITH SAID AFOREMENTIONED GASOLINE FRACTIONS TO PRODUCE APREMIUM GASOLINE HAVING AN ACTANE RATING SENSITIVITY NO GREATER THAN7.5.